In certain types of medical emergencies a patient's heart stops working. This stops the blood flow, without which the patient may die. Cardio Pulmonary Resuscitation (CPR) can forestall the risk of death. CPR includes performing repeated chest compressions to the chest of the patient so as to cause their blood to circulate some. CPR also includes delivering rescue breaths to the patient. CPR is intended to merely maintain the patient until a more definite therapy is made available, such as defibrillation. Defibrillation is an electrical shock deliberately delivered to a person in the hope of correcting their heart rhythm.
The repeated chest compressions of CPR are actually compressions alternating with releases. They cause the blood to circulate some, which can prevent damage to organs like the brain. For making this blood circulation effective, guidelines by medical experts such as the American Heart Association dictate suggested parameters for chest compressions, such as the frequency, the depth reached, fully releasing after a compression, and so on. The releases are also called decompressions.
Traditionally, CPR has been performed manually. A number of people have been trained in CPR, including some who are not in the medical professions just in case. However, manual CPR might be ineffective, and being ineffective it may lead to irreversible damage to the patient's vital organs, such as the brain and the heart. The rescuer at the moment might not be able to recall their training, especially under the stress of the moment. And even the best trained rescuer can become quickly fatigued from performing chest compressions, at which point their performance might be degraded. Indeed, chest compressions that are not frequent enough, not deep enough, or not followed by a full decompression may fail to maintain blood circulation.
The risk of ineffective chest compressions has been addressed with CPR chest compression machines. Such machines have been known by a number of names, for example CPR chest compression machines, mechanical CPR devices, cardiac compressors and so on.
CPR chest compression machines repeatedly compress and release the chest of the patient. Such machines can be programmed so that they will automatically compress and release at the recommended rate or frequency, and can reach a specific depth within the recommended range. Some of these machines can even exert force upwards during decompressions. Sometimes the feature can even pull the chest higher than it would be while at rest—a feature that is called active decompression.
At present, most CPR chest compression machines repeat the same type of compressions over and over, pressing each time at the same location of the patient chest. This precise consistency is non-physiologic and may miss an opportunity to better move blood through each part of the patient's circulatory systems.